Gas turbines, including those used for propelling military vehicles, include two or more opposed bearings which must be continuously lubricated during gas turbine usage. This is accomplished by means of a lubricating system which provides the bearings with a lubricating fluid, such as natural or synthetic oil, to not only lubricate the bearings but to also provide for cooling.
When the gas turbine is shut down after usage, the residual heat from the turbine (which may be hundreds of degrees Fahrenheit) soaks back to the bearings leading to a possible coking condition. Basically, coking is the result of the lubricant becoming an oxidized solid oil deposit on the bearing surface and in the lubricant delivery system that can lead to insufficient lubricant supply to the bearings. This can result in engine seizure and/or a requirement for a complete engine overhaul, which is undesirable, particularly in tactical combat situations.
Accordingly, it is a primary object of the present invention to provide apparatus which reduces, or eliminates coking problems in rotating machinery, particularly, in gas turbines which shut down at high temperatures.